/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 */

/* ip.c
 *
 * This is the code for the IP layer for IPv6.
 *
 */

#include "lwip/opt.h"

#if LWIP_IPV6					/* don't build if not configured for use in lwipopts.h */

#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/netif.h"
#include "lwip/ip.h"
#include "lwip/ip6.h"
#include "lwip/ip6_addr.h"
#include "lwip/ip6_frag.h"
#include "lwip/icmp6.h"
#include "lwip/raw.h"
#include "lwip/udp.h"
#include "lwip/priv/tcp_priv.h"
#include "lwip/dhcp6.h"
#include "lwip/nd6.h"
#include "lwip/mld6.h"
#include "lwip/debug.h"
#include "lwip/stats.h"

#include "lwip/arch/perf.h"
#ifdef LWIP_HOOK_FILENAME
#include LWIP_HOOK_FILENAME
#endif

static struct icmp6_hdr icmp6_prev_hdr[1] = { 0, };
/**
 * To save previous ICMP6 Packet, icmp6_prev_hdr is needed.
 *
 * @return The pointer of icmp6_prev_hdr.
 */
struct icmp6_hdr *icmp6_get_prev_hdr(void)
{
	return icmp6_prev_hdr;
}

/**
 * Finds the appropriate network interface for a given IPv6 address. It tries to select
 * a netif following a sequence of heuristics:
 * 1) if there is only 1 netif, return it
 * 2) if the destination is a link-local address, try to match the src address to a netif.
 *    this is a tricky case because with multiple netifs, link-local addresses only have
 *    meaning within a particular subnet/link.
 * 3) tries to match the destination subnet to a configured address
 * 4) tries to find a router
 * 5) tries to match the source address to the netif
 * 6) returns the default netif, if configured
 *
 * @param src the source IPv6 address, if known
 * @param dest the destination IPv6 address for which to find the route
 * @return the netif on which to send to reach dest
 */
struct netif *ip6_route(const ip6_addr_t *src, const ip6_addr_t *dest)
{
	struct netif *netif;
	s8_t i;

	/* If single netif configuration, fast return. */
	if ((netif_list != NULL) && (netif_list->next == NULL)) {
		if (!netif_is_up(netif_list) || !netif_is_link_up(netif_list)) {
			return NULL;
		}
		return netif_list;
	}

	/* Special processing for link-local addresses. */
	if (ip6_addr_islinklocal(dest)) {
		if (ip6_addr_isany(src)) {
			/* Use default netif, if Up. */
			if (netif_default == NULL || !netif_is_up(netif_default) || !netif_is_link_up(netif_default)) {
				return NULL;
			}
			return netif_default;
		}

		/* Try to find the netif for the source address, checking that link is up. */
		for (netif = netif_list; netif != NULL; netif = netif->next) {
			if (!netif_is_up(netif) || !netif_is_link_up(netif)) {
				continue;
			}
			for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
				if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && ip6_addr_cmp(src, netif_ip6_addr(netif, i))) {
					return netif;
				}
			}
		}

		/* netif not found, use default netif, if up */
		if (netif_default == NULL || !netif_is_up(netif_default) || !netif_is_link_up(netif_default)) {
			return NULL;
		}
		return netif_default;
	}

	/* we come here for non-link-local addresses */
#ifdef LWIP_HOOK_IP6_ROUTE
	netif = LWIP_HOOK_IP6_ROUTE(src, dest);
	if (netif != NULL) {
		return netif;
	}
#endif

	/* See if the destination subnet matches a configured address. */
	for (netif = netif_list; netif != NULL; netif = netif->next) {
		if (!netif_is_up(netif) || !netif_is_link_up(netif)) {
			continue;
		}
		for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
			if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && ip6_addr_netcmp(dest, netif_ip6_addr(netif, i))) {
				return netif;
			}
		}
	}

	/* Get the netif for a suitable router. */
	netif = nd6_find_route(dest);
	if ((netif != NULL) && netif_is_up(netif) && netif_is_link_up(netif)) {
		return netif;
	}

	/* try with the netif that matches the source address. */
	if (!ip6_addr_isany(src)) {
		for (netif = netif_list; netif != NULL; netif = netif->next) {
			if (!netif_is_up(netif) || !netif_is_link_up(netif)) {
				continue;
			}
			for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
				if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && ip6_addr_cmp(src, netif_ip6_addr(netif, i))) {
					return netif;
				}
			}
		}
	}
#if LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF
	/* loopif is disabled, loopback traffic is passed through any netif */
	if (ip6_addr_isloopback(dest)) {
		/* don't check for link on loopback traffic */
		if (netif_default != NULL && netif_is_up(netif_default)) {
			return netif_default;
		}
		/* default netif is not up, just use any netif for loopback traffic */
		for (netif = netif_list; netif != NULL; netif = netif->next) {
			if (netif_is_up(netif)) {
				return netif;
			}
		}
		return NULL;
	}
#endif							/* LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF */

	/* no matching netif found, use default netif, if up */
	if ((netif_default == NULL) || !netif_is_up(netif_default) || !netif_is_link_up(netif_default)) {
		return NULL;
	}
	return netif_default;
}

/**
 * @ingroup ip6
 * Select the best IPv6 source address for a given destination
 * IPv6 address. Loosely follows RFC 3484. "Strong host" behavior
 * is assumed.
 *
 * @param netif the netif on which to send a packet
 * @param dest the destination we are trying to reach
 * @return the most suitable source address to use, or NULL if no suitable
 *         source address is found
 */
const ip_addr_t *ip6_select_source_address(struct netif *netif, const ip6_addr_t *dest)
{
	const ip_addr_t *src = NULL;
	u8_t i;

	/* If dest is link-local, choose a link-local source. */
	if (ip6_addr_islinklocal(dest) || ip6_addr_ismulticast_linklocal(dest) || ip6_addr_ismulticast_iflocal(dest)) {
		for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
			if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && ip6_addr_islinklocal(netif_ip6_addr(netif, i))) {
				return netif_ip_addr6(netif, i);
			}
		}
	}

	/* Choose a site-local with matching prefix. */
	if (ip6_addr_issitelocal(dest) || ip6_addr_ismulticast_sitelocal(dest)) {
		for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
			if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && ip6_addr_issitelocal(netif_ip6_addr(netif, i)) && ip6_addr_netcmp(dest, netif_ip6_addr(netif, i))) {
				return netif_ip_addr6(netif, i);
			}
		}
	}

	/* Choose a unique-local with matching prefix. */
	if (ip6_addr_isuniquelocal(dest) || ip6_addr_ismulticast_orglocal(dest)) {
		for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
			if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && ip6_addr_isuniquelocal(netif_ip6_addr(netif, i)) && ip6_addr_netcmp(dest, netif_ip6_addr(netif, i))) {
				return netif_ip_addr6(netif, i);
			}
		}
	}

	/* Choose a global with best matching prefix. */
	if (ip6_addr_isglobal(dest) || ip6_addr_ismulticast_global(dest)) {
		for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
			if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && ip6_addr_isglobal(netif_ip6_addr(netif, i))) {
				if (src == NULL) {
					src = netif_ip_addr6(netif, i);
				} else {
					/* Replace src only if we find a prefix match. */
					/* @todo find longest matching prefix. */
					if ((!(ip6_addr_netcmp(ip_2_ip6(src), dest))) && ip6_addr_netcmp(netif_ip6_addr(netif, i), dest)) {
						src = netif_ip_addr6(netif, i);
					}
				}
			}
		}
		if (src != NULL) {
			return src;
		}
	}

	/* Last resort: see if arbitrary prefix matches. */
	for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
		if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && ip6_addr_netcmp(dest, netif_ip6_addr(netif, i))) {
			return netif_ip_addr6(netif, i);
		}
	}

	return NULL;
}

#if LWIP_IPV6_FORWARD
/**
 * Forwards an IPv6 packet. It finds an appropriate route for the
 * packet, decrements the HL value of the packet, and outputs
 * the packet on the appropriate interface.
 *
 * @param p the packet to forward (p->payload points to IP header)
 * @param iphdr the IPv6 header of the input packet
 * @param inp the netif on which this packet was received
 */
static void ip6_forward(struct pbuf *p, struct ip6_hdr *iphdr, struct netif *inp)
{
	struct netif *netif;

	/* do not forward link-local or loopback addresses */
	if (ip6_addr_islinklocal(ip6_current_dest_addr()) || ip6_addr_isloopback(ip6_current_dest_addr())) {
		LWIP_DEBUGF(IP6_DEBUG, ("ip6_forward: not forwarding link-local address.\n"));
		IP6_STATS_INC(ip6.rterr);
		IP6_STATS_INC(ip6.drop);
		return;
	}

	/* Find network interface where to forward this IP packet to. */
	netif = ip6_route(IP6_ADDR_ANY6, ip6_current_dest_addr());
	if (netif == NULL) {
		LWIP_DEBUGF(IP6_DEBUG, ("ip6_forward: no route for %" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F "\n", IP6_ADDR_BLOCK1(ip6_current_dest_addr()), IP6_ADDR_BLOCK2(ip6_current_dest_addr()), IP6_ADDR_BLOCK3(ip6_current_dest_addr()), IP6_ADDR_BLOCK4(ip6_current_dest_addr()), IP6_ADDR_BLOCK5(ip6_current_dest_addr()), IP6_ADDR_BLOCK6(ip6_current_dest_addr()), IP6_ADDR_BLOCK7(ip6_current_dest_addr()), IP6_ADDR_BLOCK8(ip6_current_dest_addr())));
#if LWIP_ICMP6
		/* Don't send ICMP messages in response to ICMP messages */
		if (IP6H_NEXTH(iphdr) != IP6_NEXTH_ICMP6) {
			icmp6_dest_unreach(p, ICMP6_DUR_NO_ROUTE);
		}
#endif							/* LWIP_ICMP6 */
		IP6_STATS_INC(ip6.rterr);
		IP6_STATS_INC(ip6.drop);
		return;
	}
	/* Do not forward packets onto the same network interface on which
	 * they arrived. */
	if (netif == inp) {
		LWIP_DEBUGF(IP6_DEBUG, ("ip6_forward: not bouncing packets back on incoming interface.\n"));
		IP6_STATS_INC(ip6.rterr);
		IP6_STATS_INC(ip6.drop);
		return;
	}

	/* decrement HL */
	IP6H_HOPLIM_SET(iphdr, IP6H_HOPLIM(iphdr) - 1);
	/* send ICMP6 if HL == 0 */
	if (IP6H_HOPLIM(iphdr) == 0) {
#if LWIP_ICMP6
		/* Don't send ICMP messages in response to ICMP messages */
		if (IP6H_NEXTH(iphdr) != IP6_NEXTH_ICMP6) {
			icmp6_time_exceeded(p, ICMP6_TE_HL);
		}
#endif							/* LWIP_ICMP6 */
		IP6_STATS_INC(ip6.drop);
		return;
	}

	if (netif->mtu && (p->tot_len > netif->mtu)) {
#if LWIP_ICMP6
		/* Don't send ICMP messages in response to ICMP messages */
		if (IP6H_NEXTH(iphdr) != IP6_NEXTH_ICMP6) {
			icmp6_packet_too_big(p, netif->mtu);
		}
#endif							/* LWIP_ICMP6 */
		IP6_STATS_INC(ip6.drop);
		return;
	}

	LWIP_DEBUGF(IP6_DEBUG, ("ip6_forward: forwarding packet to %" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F "\n", IP6_ADDR_BLOCK1(ip6_current_dest_addr()), IP6_ADDR_BLOCK2(ip6_current_dest_addr()), IP6_ADDR_BLOCK3(ip6_current_dest_addr()), IP6_ADDR_BLOCK4(ip6_current_dest_addr()), IP6_ADDR_BLOCK5(ip6_current_dest_addr()), IP6_ADDR_BLOCK6(ip6_current_dest_addr()), IP6_ADDR_BLOCK7(ip6_current_dest_addr()), IP6_ADDR_BLOCK8(ip6_current_dest_addr())));

	/* transmit pbuf on chosen interface */
	netif->output_ip6(netif, p, ip6_current_dest_addr());
	IP6_STATS_INC(ip6.fw);
	IP6_STATS_INC(ip6.xmit);
	return;
}
#endif							/* LWIP_IPV6_FORWARD */

/**
 * This function is called by the network interface device driver when
 * an IPv6 packet is received. The function does the basic checks of the
 * IP header such as packet size being at least larger than the header
 * size etc. If the packet was not destined for us, the packet is
 * forwarded (using ip6_forward).
 *
 * Finally, the packet is sent to the upper layer protocol input function.
 *
 * @param p the received IPv6 packet (p->payload points to IPv6 header)
 * @param inp the netif on which this packet was received
 * @return ERR_OK if the packet was processed (could return ERR_* if it wasn't
 *         processed, but currently always returns ERR_OK)
 */

err_t ip6_input(struct pbuf *p, struct netif *inp)
{
	struct ip6_hdr *ip6hdr;
	struct netif *netif;
	u8_t *nexth;
	u16_t hlen;					/* the current header length */
	u8_t i;
#if 0							/*IP_ACCEPT_LINK_LAYER_ADDRESSING */
	@todo int check_ip_src = 1;
#endif							/* IP_ACCEPT_LINK_LAYER_ADDRESSING */

	IP6_STATS_INC(ip6.recv);

	// [TAHI ND#127]
	ip_data.is_atomic_frag = 1;

	/* identify the IP header */
	ip6hdr = (struct ip6_hdr *)p->payload;
	if (IP6H_V(ip6hdr) != 6) {
		LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_LEVEL_WARNING, ("IPv6 packet dropped due to bad version number %" U32_F "\n", IP6H_V(ip6hdr)));
		pbuf_free(p);
		IP6_STATS_INC(ip6.err);
		IP6_STATS_INC(ip6.drop);
		return ERR_OK;
	}
#ifdef LWIP_HOOK_IP6_INPUT
	if (LWIP_HOOK_IP6_INPUT(p, inp)) {
		/* the packet has been eaten */
		return ERR_OK;
	}
#endif

	/* header length exceeds first pbuf length, or ip length exceeds total pbuf length? */
	if ((IP6_HLEN > p->len) || ((IP6H_PLEN(ip6hdr) + IP6_HLEN) > p->tot_len)) {
		if (IP6_HLEN > p->len) {
			LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IPv6 header (len %" U16_F ") does not fit in first pbuf (len %" U16_F "), IP packet dropped.\n", (u16_t) IP6_HLEN, p->len));
		}
		if ((IP6H_PLEN(ip6hdr) + IP6_HLEN) > p->tot_len) {
			LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IPv6 (plen %" U16_F ") is longer than pbuf (len %" U16_F "), IP packet dropped.\n", (u16_t)(IP6H_PLEN(ip6hdr) + IP6_HLEN), p->tot_len));
		}
		/* free (drop) packet pbufs */
		pbuf_free(p);
		IP6_STATS_INC(ip6.lenerr);
		IP6_STATS_INC(ip6.drop);
		return ERR_OK;
	}

	/* Trim pbuf. This should have been done at the netif layer,
	 * but we'll do it anyway just to be sure that its done. */
	pbuf_realloc(p, IP6_HLEN + IP6H_PLEN(ip6hdr));

	/* copy IP addresses to aligned ip6_addr_t */
	ip_addr_copy_from_ip6(ip_data.current_iphdr_dest, ip6hdr->dest);
	ip_addr_copy_from_ip6(ip_data.current_iphdr_src, ip6hdr->src);

	/* Don't accept virtual IPv4 mapped IPv6 addresses.
	 * Don't accept multicast source addresses. */
	if (ip6_addr_isipv4mappedipv6(ip_2_ip6(&ip_data.current_iphdr_dest)) || ip6_addr_isipv4mappedipv6(ip_2_ip6(&ip_data.current_iphdr_src)) || ip6_addr_ismulticast(ip_2_ip6(&ip_data.current_iphdr_src))) {
		IP6_STATS_INC(ip6.err);
		IP6_STATS_INC(ip6.drop);
		return ERR_OK;
	}

	/* current header pointer. */
	ip_data.current_ip6_header = ip6hdr;

	/* In netif, used in case we need to send ICMPv6 packets back. */
	ip_data.current_netif = inp;
	ip_data.current_input_netif = inp;

	/* match packet against an interface, i.e. is this packet for us? */
	if (ip6_addr_ismulticast(ip6_current_dest_addr())) {
		if (netif_is_up(inp)) {
			/* Always joined to multicast if-local and link-local all-nodes group. */
			if (ip6_addr_isallnodes_iflocal(ip6_current_dest_addr()) || ip6_addr_isallnodes_linklocal(ip6_current_dest_addr())) {
				netif = inp;
			}
#if LWIP_IPV6_MLD
			else if (mld6_lookfor_group(inp, ip6_current_dest_addr())) {
				netif = inp;
			}
#else							/* LWIP_IPV6_MLD */
			else if (ip6_addr_issolicitednode(ip6_current_dest_addr())) {
				/* Filter solicited node packets when MLD is not enabled
				 * (for Neighbor discovery). */
				netif = NULL;
				for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
					if (ip6_addr_isvalid(netif_ip6_addr_state(inp, i)) && ip6_addr_cmp_solicitednode(ip6_current_dest_addr(), netif_ip6_addr(inp, i))) {
						netif = inp;
						LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: solicited node packet accepted on interface %c%c\n", netif->name[0], netif->name[1]));
						break;
					}
				}
			}
#endif							/* LWIP_IPV6_MLD */
			else {
				netif = NULL;
			}
		} else {
			netif = NULL;
		}
	} else {
		/* start trying with inp. if that's not acceptable, start walking the
		   list of configured netifs.
		   'first' is used as a boolean to mark whether we started walking the list */
		int first = 1;
		netif = inp;
		do {
			/* interface is up? */
			if (netif_is_up(netif)) {
				/* unicast to this interface address? address configured? */
				for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
					if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && ip6_addr_cmp(ip6_current_dest_addr(), netif_ip6_addr(netif, i))) {
						/* exit outer loop */
						goto netif_found;
					}
				}
			}
			if (first) {
				if (ip6_addr_islinklocal(ip6_current_dest_addr())
#if !LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF
					|| ip6_addr_isloopback(ip6_current_dest_addr())
#endif							/* !LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF */
				   ) {
					/* Do not match link-local addresses to other netifs. The loopback
					 * address is to be considered link-local and packets to it should be
					 * dropped on other interfaces, as per RFC 4291 Sec. 2.5.3. This
					 * requirement cannot be implemented in the case that loopback
					 * traffic is sent across a non-loopback interface, however.
					 */
					netif = NULL;
					break;
				}
				first = 0;
				netif = netif_list;
			} else {
				netif = netif->next;
			}
			if (netif == inp) {
				netif = netif->next;
			}
		} while (netif != NULL);
netif_found:
		LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet accepted on interface %c%c\n", netif ? netif->name[0] : 'X', netif ? netif->name[1] : 'X'));
	}

	/* "::" packet source address? (used in duplicate address detection) */
	if (ip6_addr_isany(ip6_current_src_addr()) && (!ip6_addr_issolicitednode(ip6_current_dest_addr()))) {
		/* packet source is not valid */
		/* free (drop) packet pbufs */
		LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with src ANY_ADDRESS dropped\n"));
		pbuf_free(p);
		IP6_STATS_INC(ip6.drop);
		goto ip6_input_cleanup;
	}

	/* packet not for us? */
	if (netif == NULL) {
		/* packet not for us, route or discard */
		LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_TRACE, ("ip6_input: packet not for us.\n"));
#if LWIP_IPV6_FORWARD
		/* non-multicast packet? */
		if (!ip6_addr_ismulticast(ip6_current_dest_addr())) {
			/* try to forward IP packet on (other) interfaces */
			ip6_forward(p, ip6hdr, inp);
		}
#endif							/* LWIP_IPV6_FORWARD */
		pbuf_free(p);
		goto ip6_input_cleanup;
	}

	/* current netif pointer. */
	ip_data.current_netif = netif;

	/* Save next header type. */
	nexth = &IP6H_NEXTH(ip6hdr);

	/* Init header length. */
	hlen = ip_data.current_ip_header_tot_len = IP6_HLEN;

	/* Move to payload. */
	pbuf_header(p, -IP6_HLEN);

	/* Process known option extension headers, if present. */
	while (*nexth != IP6_NEXTH_NONE) {
		switch (*nexth) {
		case IP6_NEXTH_HOPBYHOP: {
			s32_t opt_offset;
			struct ip6_hbh_hdr *hbh_hdr;
			struct ip6_opt_hdr *opt_hdr;
			LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with Hop-by-Hop options header\n"));

			hbh_hdr = (struct ip6_hbh_hdr *)p->payload;

			/* Get next header type. */
			nexth = &IP6_HBH_NEXTH(hbh_hdr);

			/* Get the header length. */
			hlen = 8 * (1 + hbh_hdr->_hlen);
			ip_data.current_ip_header_tot_len += hlen;

			/* Skip over this header. */
			if (hlen > p->len) {
				LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IPv6 options header (hlen %" U16_F ") does not fit in first pbuf (len %" U16_F "), IPv6 packet dropped.\n", hlen, p->len));
				/* free (drop) packet pbufs */
				pbuf_free(p);
				IP6_STATS_INC(ip6.lenerr);
				IP6_STATS_INC(ip6.drop);
				goto ip6_input_cleanup;
			}

			/* The extended option header starts right after Hop-by-Hop header. */
			opt_offset = IP6_HBH_HLEN;
			while (opt_offset < hlen) {
				s32_t opt_dlen = 0;

				opt_hdr = (struct ip6_opt_hdr *)((u8_t *)hbh_hdr + opt_offset);

				switch (IP6_OPT_TYPE(opt_hdr)) {
				/* TODO: process IPV6 Hop-by-Hop option data */
				case IP6_PAD1_OPTION:
					/* PAD1 option deosn't have length and value field */
					opt_dlen = -1;
					break;
				case IP6_PADN_OPTION:
					opt_dlen = IP6_OPT_DLEN(opt_hdr);
					break;
				case IP6_ROUTER_ALERT_OPTION:
					opt_dlen = IP6_OPT_DLEN(opt_hdr);
					break;
				case IP6_JUMBO_OPTION:
					opt_dlen = IP6_OPT_DLEN(opt_hdr);
					break;
				default:
					/* Check 2 MSB of Hop-by-Hop header type. */
					switch (IP6_OPT_TYPE_ACTION(opt_hdr)) {
					case 1:
						/* Discard the packet. */
						LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with invalid Hop-by-Hop option type dropped.\n"));
						pbuf_free(p);
						IP6_STATS_INC(ip6.drop);
						goto ip6_input_cleanup;
					case 2:
						/* Send ICMP Parameter Problem */
						icmp6_param_problem(p, ICMP6_PP_OPTION, (u32_t)&IP6_OPT_TYPE(opt_hdr) - (u32_t)ip6_current_header());
						LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with invalid Hop-by-Hop option type dropped.\n"));
						pbuf_free(p);
						IP6_STATS_INC(ip6.drop);
						goto ip6_input_cleanup;
					case 3:
						/* Send ICMP Parameter Problem if destination address is not a multicast address */
						if (!ip6_addr_ismulticast(ip6_current_dest_addr())) {
							icmp6_param_problem(p, ICMP6_PP_OPTION, (u32_t)&IP6_OPT_TYPE(opt_hdr) - (u32_t)ip6_current_header());
						}
						LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with invalid Hop-by-Hop option type dropped.\n"));
						pbuf_free(p);
						IP6_STATS_INC(ip6.drop);
						goto ip6_input_cleanup;
					default:
						/* Skip over this option. */
						opt_dlen = IP6_OPT_DLEN(opt_hdr);
						break;
					}
					break;
				}

				/* Adjust the offset to move to the next extended option header */
				opt_offset = opt_offset + IP6_OPT_HLEN + opt_dlen;
			}

			pbuf_header(p, -(s16_t) hlen);
			break;
		}
		case IP6_NEXTH_DESTOPTS: {
			s32_t opt_offset;
			struct ip6_dest_hdr *dest_hdr;
			struct ip6_opt_hdr *opt_hdr;
			LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with Destination options header\n"));

			dest_hdr = (struct ip6_dest_hdr *)p->payload;

			/* Get next header type. */
			nexth = &IP6_DEST_NEXTH(dest_hdr);

			/* Get the header length. */
			hlen = 8 * (1 + dest_hdr->_hlen);
			ip_data.current_ip_header_tot_len += hlen;
			/* Skip over this header. */
			if (hlen > p->len) {
				LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IPv6 options header (hlen %" U16_F ") does not fit in first pbuf (len %" U16_F "), IPv6 packet dropped.\n", hlen, p->len));
				/* free (drop) packet pbufs */
				pbuf_free(p);
				IP6_STATS_INC(ip6.lenerr);
				IP6_STATS_INC(ip6.drop);
				goto ip6_input_cleanup;
			}

			/* The extended option header starts right after Destination header. */
			opt_offset = IP6_DEST_HLEN;
			while (opt_offset < hlen) {
				s32_t opt_dlen = 0;

				opt_hdr = (struct ip6_opt_hdr *)((u8_t *)dest_hdr + opt_offset);

				switch (IP6_OPT_TYPE(opt_hdr)) {
				/* TODO: process IPV6 Destination option data */
				case IP6_PAD1_OPTION:
					/* PAD1 option deosn't have length and value field */
					opt_dlen = -1;
					break;
				case IP6_PADN_OPTION:
					opt_dlen = IP6_OPT_DLEN(opt_hdr);
					break;
				case IP6_ROUTER_ALERT_OPTION:
					opt_dlen = IP6_OPT_DLEN(opt_hdr);
					break;
				case IP6_JUMBO_OPTION:
					opt_dlen = IP6_OPT_DLEN(opt_hdr);
					break;
				case IP6_HOME_ADDRESS_OPTION:
					opt_dlen = IP6_OPT_DLEN(opt_hdr);
					break;
				default:
					/* Check 2 MSB of Destination header type. */
					switch (IP6_OPT_TYPE_ACTION(opt_hdr)) {
					case 1:
						/* Discard the packet. */
						LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with invalid destination option type dropped.\n"));
						pbuf_free(p);
						IP6_STATS_INC(ip6.drop);
						goto ip6_input_cleanup;
					case 2:
						/* Send ICMP Parameter Problem */
						icmp6_param_problem(p, ICMP6_PP_OPTION, (u32_t)&IP6_OPT_TYPE(opt_hdr) - (u32_t)ip6_current_header());
						LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with invalid destination option type dropped.\n"));
						pbuf_free(p);
						IP6_STATS_INC(ip6.drop);
						goto ip6_input_cleanup;
					case 3:
						/* Send ICMP Parameter Problem if destination address is not a multicast address */
						if (!ip6_addr_ismulticast(ip6_current_dest_addr())) {
							icmp6_param_problem(p, ICMP6_PP_OPTION, (u32_t)&IP6_OPT_TYPE(opt_hdr) - (u32_t)ip6_current_header());
						}
						LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with invalid destination option type dropped.\n"));
						pbuf_free(p);
						IP6_STATS_INC(ip6.drop);
						goto ip6_input_cleanup;
					default:
						/* Skip over this option. */
						opt_dlen = IP6_OPT_DLEN(opt_hdr);
						break;
					}
					break;
				}

				/* Adjust the offset to move to the next extended option header */
				opt_offset = opt_offset + IP6_OPT_HLEN + opt_dlen;
			}

			pbuf_header(p, -(s16_t) hlen);
			break;
		}
		case IP6_NEXTH_ROUTING: {
			struct ip6_rout_hdr *rout_hdr;
			LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with Routing header\n"));

			rout_hdr = (struct ip6_rout_hdr *)p->payload;

			/* Get next header type. */
			nexth = &IP6_ROUT_NEXTH(rout_hdr);

			/* Get the header length. */
			hlen = 8 * (1 + rout_hdr->_hlen);
			ip_data.current_ip_header_tot_len += hlen;

			/* Skip over this header. */
			if (hlen > p->len) {
				LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IPv6 options header (hlen %" U16_F ") does not fit in first pbuf (len %" U16_F "), IPv6 packet dropped.\n", hlen, p->len));
				/* free (drop) packet pbufs */
				pbuf_free(p);
				IP6_STATS_INC(ip6.lenerr);
				IP6_STATS_INC(ip6.drop);
				goto ip6_input_cleanup;
			}

			/* if segment left value is 0 in routing header, ignore the packet */
			if (IP6_ROUT_SEG_LEFT(rout_hdr)) {
				/* The length field of routing option header must be even */
				if (rout_hdr->_hlen & 0x1) {
					/* Discard and send parameter field error */
					icmp6_param_problem(p, ICMP6_PP_FIELD, (u32_t)&rout_hdr->_hlen - (u32_t)ip6_current_header());
					LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with invalid routing type dropped\n"));
					pbuf_free(p);
					IP6_STATS_INC(ip6.drop);
					goto ip6_input_cleanup;
				}

				switch (IP6_ROUT_TYPE(rout_hdr)) {
					/* TODO: process routing by the type */
				case IP6_ROUT_TYPE2:
					break;
				case IP6_ROUT_RPL:
					break;
				default:
					/* Discard unrecognized routing type and send parameter field error */
					icmp6_param_problem(p, ICMP6_PP_FIELD, (u32_t)&IP6_ROUT_TYPE(rout_hdr) - (u32_t)ip6_current_header());
					LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with invalid routing type dropped\n"));
					pbuf_free(p);
					IP6_STATS_INC(ip6.drop);
					goto ip6_input_cleanup;
				}
			}

			pbuf_header(p, -(s16_t) hlen);
			break;
		}
		case IP6_NEXTH_FRAGMENT: {
			struct ip6_frag_hdr *frag_hdr;
			LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with Fragment header\n"));
			frag_hdr = (struct ip6_frag_hdr *)p->payload;

			/* Get next header type. */
			nexth = &IP6_FRAG_NEXTH(frag_hdr);

			/* Fragment Header length. */
			hlen = 8;
			ip_data.current_ip_header_tot_len += hlen;

			/* Make sure this header fits in current pbuf. */
			if (hlen > p->len) {
				LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IPv6 options header (hlen %" U16_F ") does not fit in first pbuf (len %" U16_F "), IPv6 packet dropped.\n", hlen, p->len));
				/* free (drop) packet pbufs */
				pbuf_free(p);
				IP6_FRAG_STATS_INC(ip6_frag.lenerr);
				IP6_FRAG_STATS_INC(ip6_frag.drop);
				goto ip6_input_cleanup;
			}

			/* check payload length is multiple of 8 octets when mbit is set */
			if (IP6_FRAG_MBIT(frag_hdr) && (IP6H_PLEN(ip6hdr) & 0x7)) {
				/* ipv6 payload length is not multiple of 8 octets */
				icmp6_param_problem(p, ICMP6_PP_FIELD, (u32_t)&ip6hdr->_plen - (u32_t)ip6_current_header());
				LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with invalid payload length dropped\n"));
				pbuf_free(p);
				IP6_STATS_INC(ip6.drop);
				goto ip6_input_cleanup;
			}

			// [TAHI spec 64~67]
			// if first fragment doesn't contains all headers, then
			// it should send icmpv6 param problem message to sender.
			/* Is the packet the first of fragmentation? */
			if ((frag_hdr->_fragment_offset & PP_HTONS(IP6_FRAG_OFFSET_MASK)) == 0) {
				u8_t temp_nexth = IP6_FRAG_NEXTH(frag_hdr);
				u16_t temp_hlen = IP6_FRAG_HLEN;

				while (temp_nexth) {
					switch (temp_nexth) {
					case IP6_NEXTH_DESTOPTS:
					{
						struct ip6_dest_hdr *hdr = (struct ip6_dest_hdr *)((u8_t *)frag_hdr + temp_hlen);
						temp_hlen += 8 * (1 + hdr->_hlen);
						temp_nexth = hdr->_nexth;
						break;
					}
					case IP6_NEXTH_ROUTING:
					{
						struct ip6_rout_hdr *hdr = (struct ip6_rout_hdr *)((u8_t *)frag_hdr + temp_hlen);
						temp_hlen += 8 * (1 + hdr->_hlen);
						temp_nexth = hdr->_nexth;
						break;
					}
					/* Upper-Layer Header */
					case IP6_NEXTH_ICMP6:
						temp_hlen += sizeof(struct icmp6_hdr);
						temp_nexth = 0;
						break;
					default:
						temp_nexth = 0;
						break;
					}
				}

				if (temp_hlen > IP6H_PLEN(ip6hdr)) {
					/* Could not check all headers in the first frag packet */
					icmp6_param_problem(p, 3, (u32_t)NULL);
					LWIP_DEBUGF(IP6_DEBUG, ("Could not check all headers in the first frag packet.\n"));
					pbuf_free(p);
					IP6_STATS_INC(ip6.drop);
					goto ip6_input_cleanup;
				}
			}

			/* Offset == 0 and more_fragments == 0? */
			if ((frag_hdr->_fragment_offset & PP_HTONS(IP6_FRAG_OFFSET_MASK | IP6_FRAG_MORE_FLAG)) == 0) {
				// [TAHI ND#127]
				if (ip_data.is_atomic_frag == 1) {
					// let nd6 know it's atomic fragment packet
					ip_data.is_atomic_frag = 2;
				}

				/* This is a 1-fragment packet, usually a packet that we have
				 * already reassembled. Skip this header anc continue. */
				pbuf_header(p, -(s16_t) hlen);
			} else {
#if LWIP_IPV6_REASS
				/* reassemble the packet */
				p = ip6_reass(p);
				// [TAHI ND#127]
				ip_data.is_atomic_frag = 0;
				/* packet not fully reassembled yet? */
				if (p == NULL) {
					goto ip6_input_cleanup;
				}

				/* Returned p point to IPv6 header.
				 * Update all our variables and pointers and continue. */
				ip6hdr = (struct ip6_hdr *)p->payload;
				nexth = &IP6H_NEXTH(ip6hdr);
				hlen = ip_data.current_ip_header_tot_len = IP6_HLEN;
				pbuf_header(p, -IP6_HLEN);

#else							/* LWIP_IPV6_REASS */
				/* free (drop) packet pbufs */
				LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with Fragment header dropped (with LWIP_IPV6_REASS==0)\n"));
				pbuf_free(p);
				IP6_STATS_INC(ip6.opterr);
				IP6_STATS_INC(ip6.drop);
				goto ip6_input_cleanup;
#endif							/* LWIP_IPV6_REASS */
			}
			break;
		}
		default:
			goto options_done;
			break;
		}

		if (*nexth == IP6_NEXTH_HOPBYHOP) {
			/* Hop-by-Hop header comes only as a first option */
			icmp6_param_problem(p, ICMP6_PP_HEADER, (u32_t)nexth - (u32_t)ip6_current_header());
			LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: packet with Hop-by-Hop options header dropped"\
									"(this option comes only as a first option)\n"));
			pbuf_free(p);
			IP6_STATS_INC(ip6.drop);
			goto ip6_input_cleanup;
		}
	}
options_done:

	/* p points to IPv6 header again. */
	pbuf_header_force(p, (s16_t) ip_data.current_ip_header_tot_len);

	/* send to upper layers */
	LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: \n"));
	ip6_debug_print(p);
	LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: p->len %" U16_F " p->tot_len %" U16_F "\n", p->len, p->tot_len));

#if LWIP_RAW
	/* raw input did not eat the packet? */
	if (raw_input(p, inp) == 0)
#endif							/* LWIP_RAW */
	{
		switch (*nexth) {
		case IP6_NEXTH_NONE:
			pbuf_free(p);
			break;
#if LWIP_UDP
		case IP6_NEXTH_UDP:
#if LWIP_UDPLITE
		case IP6_NEXTH_UDPLITE:
#endif							/* LWIP_UDPLITE */
			/* Point to payload. */
			pbuf_header(p, -(s16_t) ip_data.current_ip_header_tot_len);
			udp_input(p, inp);
			break;
#endif							/* LWIP_UDP */
#if LWIP_TCP
		case IP6_NEXTH_TCP:
			/* Point to payload. */
			pbuf_header(p, -(s16_t) ip_data.current_ip_header_tot_len);
			tcp_input(p, inp);
			break;
#endif							/* LWIP_TCP */
#if LWIP_ICMP6
		case IP6_NEXTH_ICMP6:
			/* Point to payload. */
			pbuf_header(p, -(s16_t) ip_data.current_ip_header_tot_len);
			icmp6_input(p, inp);
			break;
#endif							/* LWIP_ICMP */
		default:
#if LWIP_ICMP6
			/* send ICMP parameter problem unless it was a multicast or ICMPv6 */
			if ((!ip6_addr_ismulticast(ip6_current_dest_addr())) && (IP6H_NEXTH(ip6hdr) != IP6_NEXTH_ICMP6)) {
				icmp6_param_problem(p, ICMP6_PP_HEADER, (u32_t)nexth - (u32_t)ip6_current_header());
			}
#endif							/* LWIP_ICMP */
			LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip6_input: Unsupported transport protocol %" U16_F "\n", (u16_t) IP6H_NEXTH(ip6hdr)));
			pbuf_free(p);
			IP6_STATS_INC(ip6.proterr);
			IP6_STATS_INC(ip6.drop);
			break;
		}
	}

ip6_input_cleanup:
	ip_data.current_netif = NULL;
	ip_data.current_input_netif = NULL;
	ip_data.current_ip6_header = NULL;
	ip_data.current_ip_header_tot_len = 0;
	ip6_addr_set_zero(ip6_current_src_addr());
	ip6_addr_set_zero(ip6_current_dest_addr());
	// [TAHI ND#127]
	ip_data.is_atomic_frag = 1;
	return ERR_OK;
}

/**
 * Sends an IPv6 packet on a network interface. This function constructs
 * the IPv6 header. If the source IPv6 address is NULL, the IPv6 "ANY" address is
 * used as source (usually during network startup). If the source IPv6 address it
 * IP6_ADDR_ANY, the most appropriate IPv6 address of the outgoing network
 * interface is filled in as source address. If the destination IPv6 address is
 * LWIP_IP_HDRINCL, p is assumed to already include an IPv6 header and
 * p->payload points to it instead of the data.
 *
 * @param p the packet to send (p->payload points to the data, e.g. next
			protocol header; if dest == LWIP_IP_HDRINCL, p already includes an
			IPv6 header and p->payload points to that IPv6 header)
 * @param src the source IPv6 address to send from (if src == IP6_ADDR_ANY, an
 *         IP address of the netif is selected and used as source address.
 *         if src == NULL, IP6_ADDR_ANY is used as source)
 * @param dest the destination IPv6 address to send the packet to
 * @param hl the Hop Limit value to be set in the IPv6 header
 * @param tc the Traffic Class value to be set in the IPv6 header
 * @param nexth the Next Header to be set in the IPv6 header
 * @param netif the netif on which to send this packet
 * @return ERR_OK if the packet was sent OK
 *         ERR_BUF if p doesn't have enough space for IPv6/LINK headers
 *         returns errors returned by netif->output
 */
err_t ip6_output_if(struct pbuf *p, const ip6_addr_t *src, const ip6_addr_t *dest, u8_t hl, u8_t tc, u8_t nexth, struct netif *netif)
{
	const ip6_addr_t *src_used = src;
	if (dest != LWIP_IP_HDRINCL) {
		if (src != NULL && ip6_addr_isany(src)) {
			src_used = ip_2_ip6(ip6_select_source_address(netif, dest));
			if ((src_used == NULL) || ip6_addr_isany(src_used)) {
				/* No appropriate source address was found for this packet. */
				LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip6_output: No suitable source address for packet.\n"));
				IP6_STATS_INC(ip6.rterr);
				return ERR_RTE;
			}
		}
	}
	return ip6_output_if_src(p, src_used, dest, hl, tc, nexth, netif);
}

/**
 * Same as ip6_output_if() but 'src' address is not replaced by netif address
 * when it is 'any'.
 */
err_t ip6_output_if_src(struct pbuf *p, const ip6_addr_t *src, const ip6_addr_t *dest, u8_t hl, u8_t tc, u8_t nexth, struct netif *netif)
{
	struct ip6_hdr *ip6hdr;
	ip6_addr_t dest_addr;

	LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p);

	/* Should the IPv6 header be generated or is it already included in p? */
	if (dest != LWIP_IP_HDRINCL) {
		/* generate IPv6 header */
		if (pbuf_header(p, IP6_HLEN)) {
			LWIP_DEBUGF(IP6_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip6_output: not enough room for IPv6 header in pbuf\n"));
			IP6_STATS_INC(ip6.err);
			return ERR_BUF;
		}

		ip6hdr = (struct ip6_hdr *)p->payload;
		LWIP_ASSERT("check that first pbuf can hold struct ip6_hdr", (p->len >= sizeof(struct ip6_hdr)));

		IP6H_HOPLIM_SET(ip6hdr, hl);
		IP6H_NEXTH_SET(ip6hdr, nexth);

		/* dest cannot be NULL here */
		ip6_addr_copy(ip6hdr->dest, *dest);

		IP6H_VTCFL_SET(ip6hdr, 6, tc, 0);
		IP6H_PLEN_SET(ip6hdr, p->tot_len - IP6_HLEN);

		if (src == NULL) {
			src = IP6_ADDR_ANY6;
		}
		/* src cannot be NULL here */
		ip6_addr_copy(ip6hdr->src, *src);

	} else {
		/* IP header already included in p */
		ip6hdr = (struct ip6_hdr *)p->payload;
		ip6_addr_copy(dest_addr, ip6hdr->dest);
		dest = &dest_addr;
	}

	if (IP6H_NEXTH(ip6hdr) == IP6_NEXTH_ICMP6) {
		struct icmp6_hdr *icmp6hdr = (struct icmp6_hdr *)((u8_t *)(ip6hdr) + IP6_HLEN);
		if (icmp6hdr->type == ICMP6_TYPE_EREQ || icmp6hdr->type == ICMP6_TYPE_EREP) {
			memset(icmp6_prev_hdr, 0, sizeof(struct icmp6_hdr));
			memcpy(icmp6_prev_hdr, icmp6hdr, sizeof(struct icmp6_hdr));
		}
	}

	IP6_STATS_INC(ip6.xmit);

	LWIP_DEBUGF(IP6_DEBUG, ("ip6_output_if: %c%c%" U16_F "\n", netif->name[0], netif->name[1], (u16_t) netif->num));

	ip6_debug_print(p);

#if ENABLE_LOOPBACK
	{
		int i;
#if !LWIP_HAVE_LOOPIF
		if (ip6_addr_isloopback(dest)) {
			return netif_loop_output(netif, p);
		}
#endif							/* !LWIP_HAVE_LOOPIF */
		for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
			if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && ip6_addr_cmp(dest, netif_ip6_addr(netif, i))) {
				/* Packet to self, enqueue it for loopback */
				LWIP_DEBUGF(IP6_DEBUG, ("netif_loop_output()\n"));
				return netif_loop_output(netif, p);
			}
		}
	}
#endif							/* ENABLE_LOOPBACK */
#if LWIP_IPV6_FRAG
	/* don't fragment if interface has mtu set to 0 [loopif] */
	if (netif->mtu && (p->tot_len > nd6_get_destination_mtu(dest, netif))) {
		return ip6_frag(p, netif, dest);
	}
#endif							/* LWIP_IPV6_FRAG */

	LWIP_DEBUGF(IP6_DEBUG, ("netif->output_ip6()\n"));
	return netif->output_ip6(netif, p, dest);
}

/**
 * Simple interface to ip6_output_if. It finds the outgoing network
 * interface and calls upon ip6_output_if to do the actual work.
 *
 * @param p the packet to send (p->payload points to the data, e.g. next
			protocol header; if dest == LWIP_IP_HDRINCL, p already includes an
			IPv6 header and p->payload points to that IPv6 header)
 * @param src the source IPv6 address to send from (if src == IP6_ADDR_ANY, an
 *         IP address of the netif is selected and used as source address.
 *         if src == NULL, IP6_ADDR_ANY is used as source)
 * @param dest the destination IPv6 address to send the packet to
 * @param hl the Hop Limit value to be set in the IPv6 header
 * @param tc the Traffic Class value to be set in the IPv6 header
 * @param nexth the Next Header to be set in the IPv6 header
 *
 * @return ERR_RTE if no route is found
 *         see ip_output_if() for more return values
 */
err_t ip6_output(struct pbuf *p, const ip6_addr_t *src, const ip6_addr_t *dest, u8_t hl, u8_t tc, u8_t nexth)
{
	struct netif *netif;
	struct ip6_hdr *ip6hdr;
	ip6_addr_t src_addr, dest_addr;

	LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p);

	if (dest != LWIP_IP_HDRINCL) {
		netif = ip6_route(src, dest);
	} else {
		/* IP header included in p, read addresses. */
		ip6hdr = (struct ip6_hdr *)p->payload;
		ip6_addr_copy(src_addr, ip6hdr->src);
		ip6_addr_copy(dest_addr, ip6hdr->dest);
		netif = ip6_route(&src_addr, &dest_addr);
	}

	if (netif == NULL) {
		LWIP_DEBUGF(IP6_DEBUG, ("ip6_output: no route for %" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F "\n", IP6_ADDR_BLOCK1(dest), IP6_ADDR_BLOCK2(dest), IP6_ADDR_BLOCK3(dest), IP6_ADDR_BLOCK4(dest), IP6_ADDR_BLOCK5(dest), IP6_ADDR_BLOCK6(dest), IP6_ADDR_BLOCK7(dest), IP6_ADDR_BLOCK8(dest)));
		IP6_STATS_INC(ip6.rterr);
		return ERR_RTE;
	}

	return ip6_output_if(p, src, dest, hl, tc, nexth, netif);
}

#if LWIP_NETIF_HWADDRHINT
/** Like ip6_output, but takes and addr_hint pointer that is passed on to netif->addr_hint
 *  before calling ip6_output_if.
 *
 * @param p the packet to send (p->payload points to the data, e.g. next
			protocol header; if dest == LWIP_IP_HDRINCL, p already includes an
			IPv6 header and p->payload points to that IPv6 header)
 * @param src the source IPv6 address to send from (if src == IP6_ADDR_ANY, an
 *         IP address of the netif is selected and used as source address.
 *         if src == NULL, IP6_ADDR_ANY is used as source)
 * @param dest the destination IPv6 address to send the packet to
 * @param hl the Hop Limit value to be set in the IPv6 header
 * @param tc the Traffic Class value to be set in the IPv6 header
 * @param nexth the Next Header to be set in the IPv6 header
 * @param addr_hint address hint pointer set to netif->addr_hint before
 *        calling ip_output_if()
 *
 * @return ERR_RTE if no route is found
 *         see ip_output_if() for more return values
 */
err_t ip6_output_hinted(struct pbuf *p, const ip6_addr_t *src, const ip6_addr_t *dest, u8_t hl, u8_t tc, u8_t nexth, u8_t *addr_hint)
{
	struct netif *netif;
	struct ip6_hdr *ip6hdr;
	ip6_addr_t src_addr, dest_addr;
	err_t err;

	LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p);

	if (dest != LWIP_IP_HDRINCL) {
		netif = ip6_route(src, dest);
	} else {
		/* IP header included in p, read addresses. */
		ip6hdr = (struct ip6_hdr *)p->payload;
		ip6_addr_copy(src_addr, ip6hdr->src);
		ip6_addr_copy(dest_addr, ip6hdr->dest);
		netif = ip6_route(&src_addr, &dest_addr);
	}

	if (netif == NULL && dest != NULL) {
		LWIP_DEBUGF(IP6_DEBUG, ("ip6_output: no route for %" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F "\n",
								IP6_ADDR_BLOCK1(dest), IP6_ADDR_BLOCK2(dest),
								IP6_ADDR_BLOCK3(dest), IP6_ADDR_BLOCK4(dest),
								IP6_ADDR_BLOCK5(dest), IP6_ADDR_BLOCK6(dest),
								IP6_ADDR_BLOCK7(dest), IP6_ADDR_BLOCK8(dest)));
		IP6_STATS_INC(ip6.rterr);
		return ERR_RTE;
	}

	NETIF_SET_HWADDRHINT(netif, addr_hint);
	err = ip6_output_if(p, src, dest, hl, tc, nexth, netif);
	NETIF_SET_HWADDRHINT(netif, NULL);

	return err;
}
#endif							/* LWIP_NETIF_HWADDRHINT */

#if LWIP_IPV6_MLD
/**
 * Add a hop-by-hop options header with a router alert option and padding.
 *
 * Used by MLD when sending a Multicast listener report/done message.
 *
 * @param p the packet to which we will prepend the options header
 * @param nexth the next header protocol number (e.g. IP6_NEXTH_ICMP6)
 * @param value the value of the router alert option data (e.g. IP6_ROUTER_ALERT_VALUE_MLD)
 * @return ERR_OK if hop-by-hop header was added, ERR_* otherwise
 */
err_t ip6_options_add_hbh_ra(struct pbuf *p, u8_t nexth, u8_t value)
{
	u8_t hlen;
	u8_t *opt_data;
	u32_t offset = 0;
	struct ip6_hbh_hdr *hbh_hdr;
	struct ip6_opt_hdr *opt_hdr;

	/* fixed 4 bytes for router alert option and 2 bytes padding */
	hlen = (sizeof(struct ip6_opt_hdr) * 2) + IP6_ROUTER_ALERT_DLEN;

	/* Move pointer to make room for hop-by-hop options header. */
	if (pbuf_header(p, (s16_t)(hlen + sizeof(struct ip6_hbh_hdr)))) {
		LWIP_DEBUGF(IP6_DEBUG, ("ip6_options: no space for options header\n"));
		IP6_STATS_INC(ip6.err);
		return ERR_BUF;
	}

	/* Set fields of Hop-by-Hop header */
	hbh_hdr = (struct ip6_hbh_hdr *)p->payload;
	IP6_HBH_NEXTH(hbh_hdr) = nexth;
	hbh_hdr->_hlen = 0;
	offset = IP6_HBH_HLEN;

	/* Set router alert options to Hop-by-Hop extended option header */
	opt_hdr = (struct ip6_opt_hdr *)((u8_t *)hbh_hdr + offset);
	IP6_OPT_TYPE(opt_hdr) = IP6_ROUTER_ALERT_OPTION;
	IP6_OPT_DLEN(opt_hdr) = IP6_ROUTER_ALERT_DLEN;
	offset += IP6_OPT_HLEN;

	/* Set router alert option data */
	opt_data = (u8_t *)hbh_hdr + offset;
	opt_data[0] = value;
	opt_data[1] = 0;
	offset += IP6_OPT_DLEN(opt_hdr);

	/* add 2 bytes padding to make 8 bytes Hop-by-Hop header length */
	opt_hdr = (struct ip6_opt_hdr *)((u8_t *)hbh_hdr + offset);
	IP6_OPT_TYPE(opt_hdr) = IP6_PADN_OPTION;
	IP6_OPT_DLEN(opt_hdr) = 0;

	return ERR_OK;
}
#endif							/* LWIP_IPV6_MLD */

#if IP6_DEBUG
/* Print an IPv6 header by using LWIP_DEBUGF
 * @param p an IPv6 packet, p->payload pointing to the IPv6 header
 */
void ip6_debug_print(struct pbuf *p)
{
	struct ip6_hdr *ip6hdr = (struct ip6_hdr *)p->payload;

	LWIP_DEBUGF(IP6_DEBUG, ("IPv6 header:\n"));
	LWIP_DEBUGF(IP6_DEBUG, ("+-------------------------------+\n"));
	LWIP_DEBUGF(IP6_DEBUG, ("| %2" U16_F " |  %3" U16_F "  |      %7" U32_F "     | (ver, class, flow)\n", IP6H_V(ip6hdr), IP6H_TC(ip6hdr), IP6H_FL(ip6hdr)));
	LWIP_DEBUGF(IP6_DEBUG, ("+-------------------------------+\n"));
	LWIP_DEBUGF(IP6_DEBUG, ("|     %5" U16_F "     |  %3" U16_F "  |  %3" U16_F "  | (plen, nexth, hopl)\n", IP6H_PLEN(ip6hdr), IP6H_NEXTH(ip6hdr), IP6H_HOPLIM(ip6hdr)));
	LWIP_DEBUGF(IP6_DEBUG, ("+-------------------------------+\n"));
	LWIP_DEBUGF(IP6_DEBUG, ("|  %4" X32_F " |  %4" X32_F " |  %4" X32_F " |  %4" X32_F " | (src)\n", IP6_ADDR_BLOCK1(&(ip6hdr->src)), IP6_ADDR_BLOCK2(&(ip6hdr->src)), IP6_ADDR_BLOCK3(&(ip6hdr->src)), IP6_ADDR_BLOCK4(&(ip6hdr->src))));
	LWIP_DEBUGF(IP6_DEBUG, ("|  %4" X32_F " |  %4" X32_F " |  %4" X32_F " |  %4" X32_F " |\n", IP6_ADDR_BLOCK5(&(ip6hdr->src)), IP6_ADDR_BLOCK6(&(ip6hdr->src)), IP6_ADDR_BLOCK7(&(ip6hdr->src)), IP6_ADDR_BLOCK8(&(ip6hdr->src))));
	LWIP_DEBUGF(IP6_DEBUG, ("+-------------------------------+\n"));
	LWIP_DEBUGF(IP6_DEBUG, ("|  %4" X32_F " |  %4" X32_F " |  %4" X32_F " |  %4" X32_F " | (dest)\n", IP6_ADDR_BLOCK1(&(ip6hdr->dest)), IP6_ADDR_BLOCK2(&(ip6hdr->dest)), IP6_ADDR_BLOCK3(&(ip6hdr->dest)), IP6_ADDR_BLOCK4(&(ip6hdr->dest))));
	LWIP_DEBUGF(IP6_DEBUG, ("|  %4" X32_F " |  %4" X32_F " |  %4" X32_F " |  %4" X32_F " |\n", IP6_ADDR_BLOCK5(&(ip6hdr->dest)), IP6_ADDR_BLOCK6(&(ip6hdr->dest)), IP6_ADDR_BLOCK7(&(ip6hdr->dest)), IP6_ADDR_BLOCK8(&(ip6hdr->dest))));
	LWIP_DEBUGF(IP6_DEBUG, ("+-------------------------------+\n"));
}
#endif							/* IP_DEBUG */

#endif							/* LWIP_IPV6 */
